The primary objective of the study is to assess the benefice of Vyvanse on the factors that cause impairments in driving behavior in individuals with ADHD using a driving simulation aimed at examining the factors that cause impairments in driving behavior in individuals with ADHD such as driving speed, collision risk, and visual attention of 60 young drivers (ages 18-24) with ADHD. We hypothesize: 1.) young adults with ADHD treated with Vyvanse will show lower velocity (speed) scores and spend less time driving over the posted speed limit in the driving simulation when compared to subjects taking a placebo; 2.) young adults with ADHD treated with Vyvanse will show a lesser likelihood to collide with a suddenly appearing peripheral object, less difficulty maintaining the vehicle within their lane, and a lesser likelihood of driving through stop signs and solid red traffic lights without slowing down when compared to subjects taking a placebo; and 3.) young adults with ADHD treated with Vyvanse will exhibit more focused visual attention on details in the visual field when compared to subjects taking a placebo while driving. In addition, young adults with ADHD treated with Vyvanse will exhibit less visual tunneling and shorter off-road glances when compared to subjects taking a placebo.

Inclusion Criteria:

• Male and female outpatients, aged 18-24 years.
• Subjects meeting full criteria for the diagnosis of DSM-IV Attention Deficit Hyperactivity Disorder (ADHD), with onset of symptoms in childhood and persistence of impairing symptoms into adulthood as determined by clinical evaluation and/or ADHD module of structured diagnostic interview, completed by the study clinician.
• Absence of pharmacological treatment for ADHD for the past month.

Exclusion Criteria:

• Any other current psychiatric or medical condition determined to be clinically significant.
• Current use of psychotropics or any medication with clinically significant CNS effects.
• Individuals who have never held a valid driver's license.
• Mental retardation (IQ < 80).
• Individuals with a history of substance dependence or abuse within the past 6 months. Pregnant or nursing females.
• Known hypersensitivity to Vyvanse or amphetamines.
• Subjects with pre-existing structural cardiac abnormalities.
• Clinically significant abnormal screening values including:
• Laboratory values determined to be clinically significant.
• Consistent readings of hypertension (>140/90) during screening period (including screening and baseline visits), defined as two or more readings (each being the average of three measurements) at a single visit with systolic blood pressure, SBP > 140 and/or diastolic blood pressure, DBP, > 90, and confirmed by manual reading.
• Subjects with isolated incidences (of triplicate average BP) of SBP > 140 and/or DBP > 90 at baseline/week 0 visit, confirmed by manual reading, which are determined to be clinically significant.

Subjects with a clinically significant abnormality according to cardiology consultation (ECGs with clinically concerning intervals including PR, QTC, QRS, will be reviewed by cardiology).